The spread of pandemic influenza in a big city could be slowed — possibly long enough to develop a targeted vaccine — by quickly...

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The spread of pandemic influenza in a big city could be slowed — possibly long enough to develop a targeted vaccine — by quickly administering anti-viral drugs, closing schools, and taking other measures to reduce person-to-person contact, according to researchers at Fred Hutchinson Cancer Research Center.

But success would depend on how quickly such measures were implemented — and whether people complied with suggestions to stay home and so-called “social distancing” methods, conclude the authors, who include Dr. M. Elizabeth Halloran and co-author Ira Longini.

The two researchers, who are professors of biostatistics at the University of Washington, were among 17 working in three groups to create mathematical computer models studying how best to contain the flu, using Chicago as the example.

Longini and some of the other researchers have presented the information to the White House and the Institute of Medicine.

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Without such interventions, the authors conclude, about 4 million of Chicago’s 8.6 million population would catch the flu within six months.

If all the interventions were used quickly, the models show that number could be cut to about 10,000 cases, Halloran said. “We can effectively reduce the number of cases and slow the pandemic.”

The research is published in the online Early Edition of PNAS, the Proceedings of the National Academy of Sciences of the United States of America.

Assumptions

Though the authors themselves caution that many of their assumptions aren’t supported by much data, the models can stimulate discussion and help find gaps in current pandemic preparedness, said Dr. Jeff Duchin of Public Health — Seattle & King County.

However, “you have to take these models with a grain of salt,” Duchin said, because some assumptions are “flat-out unrealistic.”

For example, the models assume that sick people can get anti-viral medications, such as Tamiflu, within a day.

“This is an unrealistic expectation right now,” Duchin said. “The system is overwhelmed during a typical flu season.”

The models also assumed people would be quickly identified as having the flu, Duchin noted. “We don’t have a good way to identify people with pandemic flu rapidly right now,” he said.

In addition, the model calls for the drugs to be given preventively to household contacts of sick people, but “we don’t have enough anti-viral drugs in the national stockpile even to treat all the sick people,” Duchin said.

Social distancing

The models also look at the effects of “social distancing,” which basically means reducing person-to-person contact. Halloran, Longini and their co-authors say that might mean encouraging people to work at home, or staggering workplace arrivals. It could mean closing schools and theaters or banning mass gatherings.

But not everyone thinks it’s a good idea.

Such changes could harm “the social fabric of society and community resiliency,” wrote Dr. John Middaugh, state epidemiologist for the Florida Department of Health, in last month’s Journal of the American Medical Association.

Such “frightening of the public about germs” could cause “societal estrangement,” Middaugh warned, to the point that health-care workers, first responders or law-enforcement officers could refuse to work during an outbreak.

Carol M. Ostrom: 206-464-2249 or costrom@seattletimes.com